Overview
The application range of Inconel 625 and Incoloy 825 is very close. Since Incoloy series alloys were developed to reduce the cost of superalloys, Incoloy 825 can be regarded as a fully weakened version of Inconel 625.
In this article, we will analyze the performance differences of the two alloys from various aspects.
Basic Information
Name
Inconel 625
UNS N06625
W.Nr. 2.4856
Brand
INCONEL®
Matrix
Type
Solid Solution
Strengthened Alloy
Density
8.44 g/cm³
Use Temperature
High Temperature
Name
Incoloy 825
UNS N08825
W.Nr. 2.4858
Brand
INCOLOY®
Matrix
Type
Solid Solution
Strengthened Alloy
Density
8.14 g/cm³
Use Temperature
High Temperature
Introduction
Inconel 625
INCONEL® nickel-chromium alloy 625 (UNS N06625 / W.Nr. 2.4856) is used for its high strength, excellent fabricability (including joining), and outstanding corrosion resistance. Service temperatures range from cryogenic to 1800°F (982°C).
Incoloy 825
INCOLOY® alloy 825 (UNS N08825 / W.Nr. 2.4858) is a nickel-iron-chromium alloy with additions of molybdenum, copper, and titanium. The alloy’s chemical composition is designed to provide exceptional resistance to many corrosive environments.
Chemical Composition
Purity
Inconel 625
WIN
Incoloy 825
lose
Sulfur
Sulfur has a great influence on the transient performance and durability of the alloy. Inconel 625 controls the sulfur content more strictly.
Manganese
Manganese content has little effect on the transient properties of the alloy, but it will affect the durability of the alloy. Therefore, Inconel 625 is better than Incoloy 825 in both instantaneous performance and durability.
Phosphorus
Inconel 625 is a solid solution strengthened alloy with niobium. The phosphorus element in the alloy will segregate to form a harmful phase, which is not only harmful to the performance of the alloy, but also consumes a large amount of niobium to hinder strengthening. Therefore, the phosphorus element in Inconel 625 must be strictly controlled.
Corrosion Resistance
Inconel 625
WIN
Incoloy 825
lose
Iron
Alloy 825 has more iron content than alloy 625. Although this reduces the cost of alloy 825, it also reduces the content of corrosion-resistant elements of 825.
Nickel
The nickel content of Inconel 625 is higher than that of Incoloy 825. The difference in nickel causes alloy 625 to have a better foundation for corrosion resistance.
Molybdenum
The molybdenum content of Inconel 625 is much higher than that of Incoloy 825, which makes alloy 625 more resistant to reductive corrosion.
Mechanical Behavior
Inconel 625
WIN
Incoloy 825
lose
Niobium and Tantalum
Both Inconel 625 and Incoloy 825 are solid solution strengthened alloys, but Inconel 625 is added with niobium and tantalum. The solid solution strengthening effect of niobium and tantalum is stronger than other solid solution strengthening elements. This makes Inconel 625 have higher mechanical strength.
Molybdenum
Molybdenum is also a very effective solid solution strengthening element. Alloy 625 with more molybdenum also has a better strengthening effect.
The following table compares the mechanical properties of the two alloys, and the gap can be clearly seen.
| Inconel 625 | Incoloy 825 | |
|---|---|---|
| Tensile Strenght (MPa) |
827 | 586 |
| Yield Strenght (MPa) |
414 | 241 |
Physical Properties
| Inconel 625 | Incoloy 825 | |
|---|---|---|
| Density, g/cm³ | 8.44 | 8.14 |
| Density, lb/in.³ | 0.305 | 0.294 |
| Melting Range, °F | 2350-2460 | 2500-2550 |
| Melting Range, °C | 1290-1350 | 1370-1400 |
| Permeability at 200 oersted (15.9 kA/m) | 1.0006 | 1.005 |
| Curie Temperature, °F | <-320 | <-320 |
| Curie Temperature, °C | -196 | <-196 |
Application
It can be seen that the application range of alloy 825 and alloy 625 are almost the same. This is because alloy 825 was designed as a cheaper alternative to alloy 625.
Supported Products
Inconel 625
Main Standards
Inconel 625
/
Seamless Pipe and Tube: ASTM B444, ASTM B829
Welded Pipe: ASTM B705, ASTM B775
Welded Tube: ASTM B704, ASTM B751
Welded Fittings: ASTM B366
Rod and Bar: ASTM B446
Forgings: ASTM B564
Plate, Sheet, and Strip: ASTM B443
Incoloy 825
Condensor and Heat Exchanger Tube: ASTM B163
Seamless Pipe and Tube: ASTM B423, ASTM B829
Welded Pipe: ASTM B705, ASTM B775
Welded Tube: ASTM B704, ASTM B751
Welded Fittings: ASTM B366
Rod and Bar: ASTM B425
Forgings: ASTM B564
Plate, Sheet, and Strip: ASTM B424, ASTM B906
Price
Inconel 625
high
Incoloy 825
LOW
Although the performance of Incoloy 825 is not as good as Inconel 625, it is cheaper. Therefore, when selecting materials, if the performance of alloy 825 is sufficient, then it is recommended to use alloy 825 to reduce costs.
Conclusion
Incoloy 825 is a fully weakened version of Inconel 625. (Purity, corrosion resistance, mechanical properties), but the price of Incoloy 825 is relatively cheaper and can be given priority.
We produce a variety of nickel alloy products including alloy 625 and alloy 825. If you have requirements, you can send an inquiry to us:
